Embodiments relate to a method for fabricating a light emitting device.
Nitride semiconductors are attracting much attention for the fields of optical devices and high-power electronic devices because of their high thermal stability and wide band gap energy. In particular, blue light emitting devices (LEDs), green LEDs, and UV LEDs that use nitride semiconductors have been commercialized and are being widely used.
Nitride semiconductor LEDs commercialized in recent years include a nitride semiconductor layer, which is organic-chemically deposited over a sapphire substrate that is a heterogeneous substrate. A gallium nitride (GaN) substrate having the same material as a nitride semiconductor thin film is too expensive. Thus, it is difficult to commercially utilize the GaN substrate. The sapphire substrate widely used in recent years has an electrically insulating characteristic. Thus, a nitride semiconductor LED formed on the sapphire substrate has a lateral type structure in which cathode and anode metal pads are formed in one direction of the substrate.
Generally, a lateral type LED structure has a limitation in which a portion of a light emitting layer should be etched to form a negative electrode. Also, since the electrodes are disposed on one side of the substrate, current is not uniformly injected into the light emitting layer when the current is injected. Such un-uniform injection of the current deteriorates electronic reliability and light emission efficiency.